Adhesive interactions among leukocytes and between leukocytes and endothelium are central to processes of inflammation, host defense, asthma, and cancer. These interactions are mediated by sequential molecular steps involving carbohydrates and selectins, and integrins and ICAMs. We used flow cytometry to examine the interaction of neutrophils with cells transfected with ICAM, a counter structure for the neutrophil integrins. A manuscript has been published (Lynam, 1998). In Year 17, we examined the association of novel fluorescent ligands that bind to selectins. The ligands are derived from oligonucletoide aptamers (Parma) These ligands are being used as tools to examine the acitvity of L-selectin on leukocytes following cell activation.